- The medical Latin term psychosis comes from the Greek noun psuchosis (the giving of life, the process of animating). Despite its widespread use in biomedicine and psychology, it lacks a straightforward and unambiguous definition. A classical definition of psychosis was given in 1924 by the Austrian father of psychoanalysis Sigmund Freud (1856-1939) when he wrote that "neurosis is the result of a conflict between the ego and its id, whereas psychosis is the analogous outcome of a similar disturbance in the relation between the ego and its environment (outer world)." Many textbooks of psychiatry either provide a definition in use or simply list an overview of the operational criteria of psychosis. The more restrictive among the definitions in use regard 'psychosis' as a synonym for the group of so-called positive symptoms, which comprises hallucinations, delusions, formal thought disorders, and catatonic symptoms. Less restrictive definitions may treat psychosis as a conglomerate of positive symptoms plus negative symptoms plus affective symptoms. In an even more liberal reading, psychosis is regarded as the equivalent of a mental disorder. An additional source of confusion stems from the conceptual difference between psychotic symptoms and psychotic disorders. At the clinical level of description, it is customary to regard all hallucinations as falling into the class of psychotic symptoms. However, at the pathophysiological and etiological levels of description, it is not customary to attribute all hallucinations to a psychotic disorder. As hallucinations also occur in healthy individuals, as well as in individuals with other disorders, they cannot in this sense be designated as symptoms of Psychosis per se. The lack of conceptual clarity of the term psychosis has an impressive history. During the 18th century, the term was used to denote psychological, experiential states, whereas the term neurosis was used for a large group of organic affections, defined by the absence of fever and disorders of the 'general' nervous system. This pleasingly logical set of connotations (psychosis-psychological disorder, neurosis-neurological disorder) was somehow lost during the process of medicalization. As the British historian of Psychi-atry German E. Berrios relates, "The two terms underwent major changes in meaning during the 19th century. By 1900 the membership of the class neuroses had been drastically reduced and its few members redefined as 'psychological' disorders; in contradistinction to this, the 'psychoses' came to encompass an ever growing class of disorders, whose common denominator was the claim that they were 'organic' in nature." The Austrian philosopher Ernst Freiherr von Feuchtersleben (1806-1849) has been credited with being the first - in 1845 - to devise a classification in which the psychoses were distinguished from the diseases of the nerves. As the term in its current use refers neither to the psychological nature nor to the alleged organic nature of the phenomena in question, the need for a proper definition would seem to be more urgent than ever.ReferencesBerrios, G.E. (1987). Historical aspects of psychoses: 19th century issues. British Medical Bulletin, 43, 484-498.Blom, J.D. (2004). Deconstructing schizophrenia. An analysis ofthe epistemic and nonepistemic values that govern the biomedical schizophrenia concept. Amsterdam: Boom.Freud, S. (1924). Neurosis and psychosis.In: Sigmund Freud. Collected papers. Volume 2. (1959). Translated by Riviere, J. Edited by Jones, E. New York, NY: Basic Books.Kraepelin, E. (1990). Psychiatry. A textbook for students and physicians. Volume / Translation of Volume I of the German sixth edition (1899) by Metoui, H. Edited by Quen, J.M. Canton, MA: Watson Publishing International.Von Feuchtersleben, E. (1845). Lehrbuch der ärztlichen Seelenkunde. Wien: Verlag von Carl Gerold.
Dictionary of Hallucinations. J.D. Blom. 2010.